The preent invention relates to the production of oximinosilanes, oximinogermanes and oximinostannanes such as methyl tris(methylethylketoximino) silane, and especially for the production of such materials from alkyl and alkenyl chlorosilanes such as methyltrichlorosilane and vinyl trichlorosilane.
The classical method of preparing oximinosilanes is to react a chlorosilane such as methyl trichlorosilane with a stoichiometric amount of an oxime compound such as methyl ethyl ketoxime and a stoichiometric amount of an organic base such as triethylamine. In such process, the product and the hydrochloride of the organic base must be separated one from the other, normally requiring a distillation. Difficulties have been encountered in distilling the product from the organic base hydrochloride, with explosions sometimes resulting. A variation of this process described in U.S. Pat. No. 4,126,630 involves first reacting the chlorosilane with the amine to form an intermediate, and then reacting the intermediate with oxime compound.
An alternate process which has been suggested is to react the chlorosilane with a stoichiometric amount of the sodium salt of the oxime compound (e.g. methyltrichlorosilane reacted with three moles of sodium salt of methyl ethyl ketoxime). While the by-product inorganic salt (sodium chloride) is insoluble in the oximinosilane product, it remains difficult to separate because the sodium chloride is finely dispersed in the product. Furthermore, the sodium salt of the oxime compound requires the relatively expensive sodium metal to be used in its preparation.
A. Singh et al., in J. Chem. Soc. Dalton Trans., vol. 17, pp. 1911-1913 (1972); J. Organometallic Chem., vol. 57, pp. 301-311 (1973); Ind. J. Chem., vol. 12, pp. 851-854 (1974); Syn. React. Inorg. Metal-Org. Chem., vol. 4, pp. 549-556 (1974); and Ind. J. Chem. vol. 13, pp. 1197-1199 (1975) disclose the above three processes applied to the production of various oximinosilanes, oximinogermanes and oximinostannanes.
Russian Pat. No. 435,243 (1974) to G. V. Ryasin discloses a process of reacting an oxime compound with an organochlorosilane in the presence of a metal catalyst at 90.degree. C. or above, stripping the byproduct HCl off with an inert gas. Russian Pat. No. 724,514 (1977) discloses the same process performed in a column with reduced residence times to avoid explosive decomposition of the product. See also Chem. Abstr. 91:20702n of Czeck Pat. No. 176,704.